Double-ended hydraulically actuated downhole

ABSTRACT

Hydraulic pump for use downhole in a borehole which utilizes an engine actuated by power fluid. The power fluid flows downhole to the engine which actuates a pump. The pump lifts production fluid to the surface of the earth, with the spent power fluid being comingled with the production fluid. The pump assembly has cylinders spaced from one another by a valve assembly with each of the cylinders being divided into upper and lower chambers by a piston with one side of the piston being used as the engine while the remaining side of the piston is used for pumping fluid. A common connecting rod connects together the pistons and the valve assembly, and portions of the interior of the rod is utilized for a flow passageway in a manner which enables the pump assembly to assume an extremely small cross-sectional area.

United States Patent 1191 Roeder Oct. 28, 1975 DOUBLE-ENDED HYDRAULICALLY ACTUATED DOWNHOLE [76] Inventor: George K. Roeder, PO. Box 4335,

Odessa, Tex. 79760 [22] Filed: Feb. 12, 1974 21 Appl. No.: 441,801

[52] US. Cl. 417/393 [51] Int. Cl. F04B 17/00 [58] Field of Search 417/393, 397, 401

[56] References Cited UNITED STATES PATENTS 2,503,986 4/1950 Alley 417/393 X 2,991,721 7/1961 Foster 417/393 X 3,212,445 10/1965 Coberly 417/401 Primary Examiner-C. J. l-iusar Assistant ExaminerLeonard F. Smith Attorney, Agent, or Firm-Marcus L. Bates II-I :2)-

57 ABSTRACT Hydraulic pump for use downhole in a borehole which utilizes an engine actuated by power fluid. The power fluid flows downhole to the engine which actuates a pump. The pump lifts production fluid to the surface of the earth, with the spent power fluid being comingled with the production fluid.

The pump assembly has cylinders spaced from one another by a valve assembly with each of the cylinders being divided into upper and lower chambers by a piston with one side of the piston being used as the engine while the remaining side of the piston is used for pumping fluid.

A common connecting rod connects together the pistons and the valve assembly, and portions of the interior of the rod is utilized for a flow passageway in a manner which enables the pump assembly to assume an extremely small cross-sectional area.

16 Claims, 6 Drawing Figures U.S. Patent Oct.28, 1975 Sheet 1 of4 3 ,915,595

FIG. 2

FIG. l

US. Patent Oct.28, 1975 I Sheet3 of4 3,915,595

DOUBLE-ENDED HYDRAULICALLY ACTUATED DOWNHOLE BACKGROUND OF THE INVENTION The US. Pat. Nos. to Roeder 3,703,926; Roeder 3,650,640; Roeder 3,540,814; and Coberly 3,322,069 are examples of the prior art.

l-Iydraulically actuated downhole pump assemblies are known to those skilled in the art as evidenced by the above referred to patents, and to the art cited therein, to which reference is made for futher background of this invention.

In drilling boreholes to depths exceeding 15,000 feet, it is necessary to reduce the diameter thereof for obvious reasons. Accordingly, when it becomes necessary to utilize a downhole fluid actuated pump assembly in a slim or narrow borehole, it is desirable that the pump assembly have a minimum cross-sectional area so that the pistons contained therein can be fabricated to have a maximum cross-sectional area, thereby pumping a proportionately greater volumn of production fluid for each stroke of the pump.

As evidenced by the US. Pat. No. 3,650,640, it is known to utilize a longitudinally extending hollow body member having the interior thereof divided into upper and lower chambers by a valve assembly and having opposed pistons, one in each chamber, dividing each of the chambers into upper and lower chambers, thereby enabling the valve assembly to be placed within the very closest proximity of the engine chambers.

However, in the prior art patents referred to above, it has heretofore been necessary to utilize external passageways formed either through the main body of the pump assembly or the placement of flow conduits externally of the body, with both of these undesirable expedients significantly reducing the effective crosssectional area of the engine and the pump pistons. It is therefore desirable to effectively eliminate external passageways of this type so that the cross-sectional area of the engine and pump pistons are thereby greatly increased in effective area.

SUMMARY OF THE INVENTION This invention relates to oil well tools and specifically to a hydraulically actuated downhole pump assembly having a longitudinally extending main body separated into upper and lower cylindrical chambers which are spaced from one another by a valve assembly. The upper and lower main chambers, respectively, are divided into an upper production chamber, a lower engine chamber, and an upper engine chamber and a lower production chamber by upper and lower pistons reciprocatingly and sealingly received within each of the upper and lower main chambers.

An axially aligned longitudinally extending connecting rod connects together the two pistons and extends through the upper production chamber into an inlet rod seal tube with the lower extremity of the rod extending through the lower production cylinder and into an outlet rod seal tube. Power fluid flows into the inlet rod seal tube, into the interior of the rod, and to the engine. Flow from the valve assembly is conducted into a marginal interior portion of the hollow rod, through the upper engine chamber, through the lower piston, through the lower production chamber, and into the outlet rod sealed tube, where the fluid co-mingles with the produced fluid flowing from the upper and lower production chambers. In carrying out the present invention, improvements in the valve assembly enhances the operation of the pump assembly.

Accordingly, a primary object of the present invention is the provision of a hydraulically actuated downhole pump assembly having a double acting engine and pump piston with opposite sides of the pistons being utilized as the engine and the: pump cylinder chambers.

Another object of the invention is to provide improvements in a pump assembly wherein a common connecting rod connecting together two pistons have a limited interioral axial length thereof divided into two different flow passageways which are used for controlling the flow of fluid to and from a valve assembly.

A further object of this invention is to disclose and provide improvements in a valve assembly used in combination with a double acting downhole pump assembly wherein the connecting rod controls the action of the valve assembly.

A still further object of this invention is to provide a narrow downhole pump assembly which utilizes an axially aligned connecting rod as part of the flow system for flow of fluid to and from the engine.

Another and still object is to provide improvements in a combination engine and pump assembly for use downhole in a borehole.

An additional object is to provide improvements in a hydraulically actuated downhole pump assembly by the provision of a hollow connecting rod which connects together opposed pistons so that the interior of the rod can be used in conducting fluid flow to and from a control valve assembly.

These and various other object and advantages of the invention will become readily apparent to those skilled in the art upon reading the following details of description and claims and by referring to the accompanying drawings.

The above objects are attained in accordance with the present invention by the provision of a combination of elements which are fabricated in a manner substantially as described in the above abstract and summary.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary, side elevational view of a downhole pump made in accordance with the present invention, with some parts associated therewith being shown in cross-section;

FIG. 2 is a part diagrammatical, part schematical illustration which sets forth the principle of operation of the hydraulic pump disclosed in the foregoing drawing;

FIG. 3 is a longitudinal, part cross-sectional illustra tion of one of the embodiments of the pump disclosed in the foregoing figures;

FIG. 4-A is a fragmentary, enlarged, part crosssectional view which sets forth the details of part of the pump apparatus disclosed in the foregoing figures;

FIG. 4-B is an enlarged, part cross-sectional view of part of the apparatus disclosed in FIG. 4-A; and,

FIG 5 is an enlarged, fragmentary, cross-sectional view of another embodiment of the pump assembly made in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Throughout the various figures of the drawings, wherever it is logical or convenient to do so, various similar or like parts will be identified by the same or similar numerals.

As seen in FIGS. 1 and 2, a fluid actuated downhole pump receives formation fluid at 11 and flow conducts the fluid along path 12 so that the pump apparatus can cause produced fluid to flow from the pump apparatus at 14 and uphole along flow path 15.

The pump apparatus is comprised of a longitudinally extending main body 16 having an axially extending chamber therein which is divided into an upper chamber 17 and a lower chamber 18 by the illustrated valve assembly. Upper and lower pistons 19 and 20, respectively, divide each of the upper and lower chambers into an upper production chamber 21, a lower engine chamber 22, and upper engine chamber 23, and a lower production chamber 24.

Power fluid inlet chamber is formed by the illustrated seal means 26 which slidably receives a marginal end portion of connecting rod 27 in a reciprocating manner therein. A marginal interior length of the connecting rod is hollow so that fluid can flow thereinto as indicated by the numeral 28. The lower marginal end portion 29 of the connecting rod is reciprocatingly received in a slidable manner by seal means 30 so that fluid is contained in the illustrated outlet rod sealed tube 31.

The before mentioned valve assembly is seen at 32 and is provided with an upwardly directed upper rod seal tube 33 having seal means 34 at the free end portion thereof. Downwardly extending lower rod seal tube 35 has a similar seal means 36 at the lower terminal end portion thereof. Numeral 37 indicates that the central passageway 28 formed along the axial center line of the connecting rod is discontinuous so that fluid must flow from 25 into the rod at 28, out of the rod at port 38, because of the presence of obstruction 37. Similarly, fluid flows from the valve assembly into the rod seal tube 35, into the lower portion of the hollow rod, and out of the lower end portion of the rod at 29.

Outlet ports form a flow path 40 from the valve assembly into an engine chamber 22, and a flow path 41 into the engine chamber 23.

Hence, it is evident that a power fluid flow path extends from chamber 25 through the hollow rod into the upper rod seal tube 33 by means of port 38, and to the valve assembly. A spent power fluid flow path is formed from the valve assembly into the rod seal tube 35, into the port 39, through the rod and to the lower terminal end 29 of the control rod, into the lowermost seal tube 31, and to outlet 14. Alternate flow paths 40, 41 are formed from the valve assembly to each of the engine chambers. The valve assembly alternately connect the power fluid source to flow path 40 and the spent power fluid to flow path 41 thereby causing the upper and lower pistons to reciprocate within the upper and lower cylindrical chambers. This action causes formation fluid to flow into and out of the production cylinders 21, 24, in response to movement of the pistons. The action of the connecting rod as it reciprocat es within the pump assembly causes the valve assembly to shift, thereby alternately connecting together each of the alternate passageways in a cyclic manner.

Looking now to the details of the specific embodiment illustrated in FIGS. 3 and 4, and in particularly to FIG. 3, wherein one manner by which the foregoing inventative concept is set forth in greater detail. As particularly seen illustrated in FIG. 3, casing 42 of a well bore is concentrically arranged relative to production tubing 43 with the production tubing being provided with an upper and lower seal means 44, 45, for maintaining various fluids separated from one another as will be discussed in greater detail later on in this disclosure.

A packer device 46 isolates a source of production fluid 47 from annulus 48. A foot valve assembly 49 precludes flow between chambers 47 and 48 when the free type pump, for example, is removed therefrom.

The lower seal assembly is provided with port 50 so that produced fluid can flow into annulus 48 and to the surface of the ground. Inlet port 51 is connected to supply production fluid to the lower production chamber 24, while inlet portion 52 is connected to supply production fluid to the upper production chamber 21. Production outlet port 53 enables produced fluid to flow from chamber 21 into the annulus 48.

The upper seal 44 has spaced circumferentially extending seal means 54 which sealingly engage an upper marginal outer surface area of the main body of the pump, thereby isolating the power fluid source 25' from the production tubing annulus. The lower seal means has spaced seals 56 which sealingly engage the lower marginal end of the pump so that the inlet of the pump is isolated from the outlet port 14.

The casing is perforated at 57 in the usual manner so that production fluid can flow into the chamber 47. Packer element 58 enables the pump assembly to be forced into and out of the borehole. Fishing neck 59 forms the uppermost end of the pump while power fluid can flow into the pump assembly by means of the ports indicated by the numerals 60.

FIG. 4 sets forth the constructional details of the valve assembly previously disclosed in the foregoing figures. The upper marginal portion of the main body is formed into an upper cylinder 62 with the lower end of the cylinder being threadedly attached to adapter 64 which in turn is threadedly affixed to a valve body 65. Lower adapter 66 threadedly engages the lower cylinder 63 and has a longitudinally extending axially aligned passageway formed therethrough of varying diameters so that a sliding valve element 67 can be reciprocatingly received therewithin with the control rod, valve element, and valve body all being concentrically arranged relative to one another.

The sliding valve element has an upper reduced portion 68 which enlarges at 69, reduces in diameter at 70,

and again enlarges in diameter to form a downwardly opening skirt member 71 having a lower terminal end portion 72. Radially spaced ports 73 may be placed in fluid communication with port 74 and annular chamber 75.

The connecting rod is provided with upper and lower circumferentially extending undercut areas 76 78, hereinafter called upper and lower flats. The upper flat 76, when the pistons downstroke, is adapted to cause the valve element to shift in a downward direction, while the lower flat, when the pistons upstroke, is adapted to cause the valve element to shift in an upward direction. Undercut area 77 communicates chamber with annular groove 80 of member 81, while undercut area 78 communicates the annular groove 80 with chamber 82. Hence, it is apparent that the annular interior groove 80 of fixed sleeve member 81 enables flow to occur across the marginal length 79 of the connecting rod.

The lower marginal outer surface area of the fixed sleeve 81 is rigidly but removably connected to the sub 66. Ports 83, 85 and annular exhaust chamber 84 provide for controlled flow of fluid for actuating the sliding valve element.

Annular power fluid flow passageway 86 is in fluid communication with annular flow passageway 87 formed between the rod and the skirt and provides a source of power fluid to flow passageway 88 when port 73, 74 are aligned with one another. Passageway 88 is connected to the lower engine chamber by means of passageways 89 and 90.

Radial flow passageways 91 continue through the sub as passageways 92 and flow through the annulus 93 formed between the reduced portion of the traveling valve element and the valve body so as to place ports 94, 95 in fluid communication with one another when the valve element is in the uppermost position. The fluid continues to flow from port 95 through port passageway 96, through port 97, and into the interior of the lower rod seal tube so that fluid can enter the hollow rod by means of port 39.

Hence, it is evident that the valve assembly alternately connects together a source of power fluid at 86 and one of the engine cylinder flow passageways 90 and 91 leading to one of the engine cylinders, and at the same time a spent power fluid outlet port 39 is connected to the remaining one of the engine cylinder flow passageways so that one of the engine chambers is exhausting spent power fluid while the other chamber is being filled with power fluid, thereby causing the double acting engine to continue to stroke in each direction.

The downhole pump disclosed in the illustrated embodiment of FIG. 5 is comprised of the before mentioned valve assembly 18 having opposed upper and lower rod seal tubes 33 and 35 within which there is slidably received in a reciprocating and sealed manner a hollow connecting rod 27 having an outlet port 38 separated from an inlet port 39 so that fluid can flow from 28, through the hollow rod, into the annulus of seal tube 33, and to the valve assembly in the before described manner. Spent power fluid flows from the valve 18 into the annulus of the lower seal tube, and into port 39 where the fluid then continues to flow in a downward direction to where it ultimately admixes with produced fluid in any suitable manner, such as described in conjunction with FIGS. 2 and 3, for example.

The upper exterior marginal end portion of the pump assembly of FIG. 5 is provided with spaced seals 126, 126 which sealingly engage the inwardly directed seal surfaces of member 54, seen in FIG. 3, so that various fluids flowing to and from the pump may be maintained separate from one another.

Ball check valve 100 permits one-way flow of fluid from production intake 102 to travel into the upper extremity of the upper production cylinder 121' as the piston 119' reciprocates therewithin.

Passageway 107 is flow connected between the annular valve chamber 107' and the production exhaust port 109, with fluid flow from the production chamber being controlled by means of the ball check valve 108.

The upper production cylinder annulus 104 is formed between the wall which forms the pump housing and the production cylinder wall, and is flow connected to the production exhaust by means of an exchange passageway 106.

The upper engine cylinder has a polished inside surface area for reciprocatingly receiving an engine piston 119 in sealed relationship therewithin. It will be noted that the relative cross-sectional areas of pistons 119 and 119 differ from one another so that a mechanical advantage is gained therebetween for lifting fluids against large hydrostatic heads.

Power fluid inlet 28 flows through the hollow rod at 27, through the passageway 128 formed within the production and engine pistons, with the passageway continuing into communication with outlet port 38 located in the annulus of the upper seal tube.

The connecting rod 27 extends into fixed relationship respective to piston 119, and. is affixed to piston 119 so that it continues through the valve assembly where it is affixed to the lower engine piston 120. Inlet port 39 provides the before mentioned flow passageway from the lower seal tube, and through the engine piston at 139, where the flow splits into two flow paths at the lateral flow ports 240.

The lateral flow ports communicate the piston passageway 139 with the rod passageway 129 so that fluid flow can occur from the lower seal tube annulus, and from the lower piston cylinder 124, through the interior of the lower connecting rod 29, where the fluid comingles with produced fluid and is pumped to the surface of the earth.

The lower production piston 120' is reciprocatingly received within the reduced diameter production cylinder 204, with the production cylinder cooperating with the concentrically arranged pump housing to form annulus 204.

Production inlet ball check valve 200 controls fluid flow through the production inlet 202 while the production passageway 206 is connected to a produced fluid outlet passageway 207 by means of the outlet production ball check valve 208. Outlet port 209 is maintained separate from formation fluid supply 111 by means of the seal 226, which sealingly cooperates with the production tubing in the illustrated manner of FIGS. 1 and 3.

In operation of the first embodiment of the invention, power fluid flows downhole through tubing 43 and into the packer nose assembly at with the fluid continuing into the upper terminal end of the connecting rod as indicated by the numeral 28. The power fluid flows through the interior of the connecting rod as it is conducted through the upper production cylinder, the upper piston, through the lower engine cylinder, into the upper rod seal tube by means of power fluid outlet 38 formed within the connecting rod. The interior passageway formed within the connecting rod is discontinuous or plugged as indicated by the numeral 37 in FIG.

' The power fluid continues to flow through annulus 86 where it is available to the valve assembly which As the pistons stroke in a downward direction, the power fluid located within the upper engine cylinder 22 flows into the radial passageways 91 and 92, annular passageway 93, passageway 96, through port 97 and into the lower seal tube 36 where the spent power fluid then flows into port 39, into the passageway formed within the connecting rod, down through the upper engine cylinder, through the lower piston, through the lower production chamber, and into the lowermost or exhaust seal tube 30, where the spent power fluid comingles with production fluid from the lower production chamber and flows through outlet ports 14 and 50 and into the casing annulus. Produced fluid from the upper production cylinder exhausts from port 53 into the casing annulus wherein it mixes with the other produced fluid and spent power fluid as it flows up the easing annulus and to the surface of the ground.

One important feature of the present invention is the presence of the spaced dual adjacent lower valve shifting grooves 77 and 78. As the lower grooves, which are spaced apart by shoulder 79, are moved into the up position, that is, when the control rod shifts up, fluid will flow from chamber 75 into the upper extremity of the upper groove, down the groove, and into the annular groove 80, across the shoulder 79, into the upper extremity of groove 78, and into the annular chamber 82, thereby enabling high pressure fluid to flow under the traveling valve element causing the valve to shift into the illustrated upper position of FIG. 4. In the absence of the shoulder 79, the seal provided by the control sleeve 81 will be shorted out, thereby letting the valve element shift back into the down position, as undercut areas 77 and 78 pass 83 and 84.

As the pump downstrokes, the upper groove 76 interconnects annular chamber 82 with chamber 84, thereby permitting fluid within chamber 82 to flow across the groove, into chamber 84, through port 85, and into the lower engine rod seal tube where the fluid is exhausted. This action enables the high pressure fluid which is effected upon the uppermost surfaces of the valve element to force the element to move in a downward direction until edge portion 95 is moved below port 74, thereby communicating ports 74 and 95 with one another.

In operation of the embodiment of FIG. 5, the downhole hydraulically actuated pump assembly is placed downhole within the production tubing and operated in the illustrated manner of FIGS. 2 and 3, although it is possible for the pump to also be operated as a fixed type if such an expedient is deemed desirable. Power oil input into the upper extremity of the hollow connectingrod flows into the interior of the rod, through the upper production piston, through the upper engine piston, out of the hollow connecting rod at 38, into the upper seal tube annulus, and to the valve assembly so that the valve assembly can alternately provide the power side of the spaced engine cylinders with power fluid, thereby causing the production pistons to reciprocate within the reduced diameter production cylinders.

As the engine pistons reciprocate within their respective cylinders, fluid contained within the upper and lower production cylinder housing, 121 and 124, must be displaced and recharged each pump stroke. Accordingly, the upper production cylinder housing is provided with flow passageways 106 and 107, which communicate with the produced fluid within the annular valve chamber 107', thereby providing a convenient source of exchange fluid.

Fluid contained within the lower production cylinder housing is placed into communication with both the spent power fluid and the produced fluid by means of the lateral ports 240, which are also in fluid communication with the lower portion of the hollow rod. Accordingly, fluid can flow into and out of the lower production cylinder housing as the lower production piston reciprocates within the lower production cylinder.

Produced fluid flows from the lower production cylinder, through production passageways 206 and 207, where the produced fluid exhausts at 209.

Spent power fluid from the valve assembly flows, into the lower seal annulus, into port 39, through the engine piston, through the lowerproduction piston, and through the lower portion of the connecting rod extension.

Ports 38 and 39 do not communicate with one another through the hollow rod, and therefore, it is expedient to make the rod of solid cross-sectional configuration between the last two recited ports.

With high pressure fluid being constantly exerted upon the upper end of the connecting rod, the danger of the valve element locking in a closed position is minimized because the constant downward pressure of the power fluid effected upon the upper surface of the rod tends to slowly reposition the valve system into proper operative position to cause the valve element to shift into one of its proper alternate positions.

Hence, should the element lock in closed position, it is unnecessary to pull the pump, because after a suitable time interval, the problem will be corrected because of the design expedients incorporated into the invention.

By the provision of the novel engine, pump, and valve combination, along with the novel flow path arrangement disclosed herein, a slim downhole pump is provided which is rugged in design, efficient and dependable in operation, and low in maintenance cost.

While a free type pump has been disclosed herein, those skilled in the art will understand that the instant invention also includes a fixed type downhole pump assembly.

I claim:

1. In a downhole hydraulically actuated pump assembly having a piston driven engine, a connecting rod attached to the piston, a pump connected to be driven by the connecting rod, and a control valve arranged to control power fluid flowing to and from the engine so that reciprocation of the engine piston causes the pump to lift fluid, the improvement comprising:

said control valve includes a valve body (65), a fixed sleeve 81, and a valve element (67) slidably received about said fixed sleeve and within said valve body; said valve body, valve element, and fixed sleeve being concentrically arranged about said connecting rod;

spaced upper and lower flats (76, 77, 78) on said connecting rod, means forming a power fluid annulus between said connecting rod and valve element, means forming a spent power fluid annulus (98) between said connecting rod and pump body, said power fluid annulus being spaced from said spent power fluid annulus by at least part of said fixed sleeve; means forming a chamber (82) between said valve body, fixed sleeve, and valve element for causing said valve element to reciprocate when power fluid is flow connected thereto; an annular chamber (80) formed between said connecting rod and the interior of said fixed sleeve, flow passageway means (92 and 88) formed in said valve body and connected to said engine;

said lower flat being comprised of two spaced undercut areas of a length to connect together said power fluid annulus (75), annular chamber (80), and chamber (82) when said connecting rod is in an upper position, to cause the valve element to shift upward, thereby connecting together said power fluid and said spent power fluid flow passageways of the engine in a manner to cause a piston of the engine to stroke downwards;

means by which said upper flat connects together said chamber (82) and said spent power fluid annulus (98) when the rod downstrokes to thereby cause the valve element to shift downward whereupon said power fluid and said spent power fluid flow passageways of the engine are connected together in a manner to cause a piston of the engine to stroke upwards.

2. A hydraulically actuated downhole pump assembly comprising a main body having upper and lower cylindrical chambers spaced from one another by a control valve assembly;

said upper and lower cylindrical chambers, respectively, having upper and lower pistons, respectively, reciprocatingly received therein; a connecting rod connected to said upper and lower pistons and adapted to stroke the pistons in either of two directions, a marginal intermediate portion of said connecting rod being received through said control valve assembly; means by which reciprocal action of said rod controls the action of said control valve assembly;

said upper portion dividing said upper cylinder chamber into an upper production chamber and a lower engine chamber;

said lower piston dividing said lower cylinder chamber into an upper engine chamber and a lower production chamber;

means including a flow conduit forming a production fluid inlet through part of said main body and into said upper and lower production chambers so that production fluid from a production formation can flow thereinto; means including a flow conduit forming a produced fluid outlet through part of said main body and from said upper and lower production chambers so that produced fluid can flow from said downhole pump;

means forming a power fluid flow path which extends into said main body, through said upper piston, through at least a marginal length of said connecting rod, and to said control valve assembly; means forming a first transfer fluid flow path connected from said control valve assembly to said lower engine chamber; means forming a second transfer fluid flow path connected from said control valve assembly to said upper engine chamber; means forming a spent power fluid flow path connected to flow from said control valve assembly, through a marginal length of said connecting rod, through said upper engine cylinder, through said lower piston, through said lower production chamber, and into flow communication with said produced fluid outlet;

and means responsive to reciprocal movement of said connecting rod for causing said control valve assembly to connect said first transfer fluid flow path to said power fluid flow path, and said spent power fluid flow path to said second transfer fluid flow path when said rod strokes in one of two directions; and,

to connect together said second transfer fluid flow path to said power fluid flow path, and said spent power fluid flow path to said first transfer fluid flow path when said rod strokes in the other of two directions;

so that fluid pressure effected in said lower and upper engine chambers causes produced fluid to flow from said upper and lower production chambers.

3. The downhole pump of claim 2 wherein said control valve assembly includes diametrically opposed spaced upwardly extending and downwardly extending rod seal assemblies, spaced marginal lengths of said connecting rod being axially positioned within said seal assemblies; the outer surface of said marginal length of said rod being spaced from the inner surface of said seal assembly to form an annulus therebetween; a port in said marginal length of saidrod communicating said annulus with the interior of said rod;

said annulus of said upwardly extending seal assembly forming part of said power fluid flow path;

said annulus of said downwardly extending seal assembly forming part of said spent power fluid flow path.

4. The pump of claim 3 wherein part of said spent power fluid outlet includes a lower marginal end portion of said connecting rod downwardly extending from said lower piston and through said lower production chamber;

a lower rod seal tube having means for sealingly receiving a lower marginal end of said rod, and with said rod seal tube having means forming an outlet connected to said produced fluid outlet.

5. The downhole pump of claim 4 wherein said control valve assembly includes a traveling element slidably received therein and slidable from a first to a second position for properly aligning the recited passageways together so that fluid flow can occur therethrough.

6. The pump of claim 2-wherein said means responsive to reciprocal movement of said connecting rod includes a traveling element slidably received therein and slidable from a first to a second position for aligning the various flow passageways together.

7. The pump of claim 2 wherein said power fluid flow path includes an upper seal means located above said upper production cylinder and sealingly receiving an upper marginal length of said connecting rod; said control valve assembly includes diametrically opposed spaced upwardly extending and downwardly extending rod seal assemblies, spaced marginal lengths of said connecting rod being axially positioned within said seal assemblies; the outer surface of said marginal length of said connecting rod being spaced from the inner surface of said seal assembly to form an annulus therebetween; a port in said marginal length of said rod communicating said annulus with the interior of said connecting rod;

said annulus of said upwardly extending seal assembly forming part of said power fluid flow path;

said annulus of said downwardly extending seal assembly forming part of said spent power fluid flow path; said power fluid flow path formed through the upper marginal end of said connecting rod being connected to said annulus of said upwardly extending seal assembly.

8. The downhole pump assembly of claim 2 wherein said upper and lower pistons are each formed with a large diameter and a small diameter portion;

said upper and lower cylinders are each formed with a large diameter and a small diameter portion;

said large and small diameter portion, respectively, of

said cylinders receiving said large and small diameter portion, respectively, of said pistons.

9. The downhole pump assembly of claim 8 wherein said small diameter portion of said upper cylinder is separated from the pump body by an annulus, means by which said annulus is flow connected to the production exhaust so that fluid can flow into and out of said annulus.

10. In a downhole hydraulically actuated pump assembly having a fluid powered engine connected to drive a production pump, a source of power fluid connected to the engine, with the production pump being connected to a source of production fluid and to a produced fluid outlet, and with the pump assembly being connected so that spent power fluid and produced fluid flows from the pump assembly uphole to the surface of the ground, the improvement comprising:

, said pump assembly comprising a main body having means forming an upper cylinder chamber, a lower cylinder chamber, a control valve, with said upper and said lower chambers being spaced from one another by said control valve;

a connecting rod, an upper and lower production seal means, an upper piston, a lower piston, said upper piston dividing said upper chamber into an upper production chamber and a lower engine chamber; said lower piston dividing said lower chamber into an upper engine chamber and a lower production chamber; said connecting rod being connected to said pistons and extending through said upper production seal means, said upper production chamber, said upper piston, said lower engine chamber, said control valve means, said upper engine cylinder, said lower piston, said lower production chamber, and through said lower seal means;

an upper rod seal tube, said upper rod seal tube being flow connected to said control valve and extending into said lower engine chamber; a lower rod seal tube, said lower rod seal tube being flow connected to said control valve and extending into said upper engine chamber; said lower production seal means being separated from said lower piston by said lower production chamber; said upper production seal means being separated from said upper piston by said upper production chamber;

means forming a first transfer flow passageway from said control valve into said lower engine chamber, means forming a second transfer flow passageway from said control valve into said upper engine cylinder;

means forming a power fluid flow passageway extending from the interior of an upper end of said pump, into the upper end of said connecting rod,

through a marginal length of said connecting rod, into said upper rod seal tube and to said control valve;

means forming a spent power fluid flow passageway from said control valve, into said lower rod seal tube, into said connecting rod, through a marginal length of said connecting rod, into said lower production seal means, and to the produced fluid outlet;

said control valve including means responsive to movement of said connecting rod in one direction for'causing said first transfer flow passageway to be connected to said power fluid flow passageway while said second transfer flow passageway is connected to said spent power fluid flow passageway; and, means responsive to movement of said rod in another direction for causing said first transfer flow passageway to be connected to said spent power fluid flow passageway while said second transfer flow passageway is connected to said power fluid flow passageway.

11. The downhole pump of claim 10 wherein said control valve includes a traveling element slidably received therein and slidable from a first to a second position for properly aligning the recited passageways together so that fluid flow can occur therethrough.

12. The downhole pump of claim 10 wherein said control valve includes diametrically opposed spaced upwardly extending and downwardly extending rod seal assemblies, spaced marginal lenths of said connecting rod being axially positioned within said seal assemblies; the outer surface of said marginal length of said rod being spaced from the inner surface of said seal assembly to form an annulus therebetween; a port in said marginal length of said rod communicating said annulus with the interior of said rod;

said annulus of said upwardly extending seal assembly forming part of said power fluid flow path;

said annulus of said downwardly extending seal assembly forming part of said spent power fluid flow path.

13. The downhole pump of claim 10 wherein said spent power fluid outlet includes a lower marginal end portion of said connecting rod downwardly extending from said lower piston and through said lower production chamber;

a lower rod seal tube having means for sealingly receiving a lower marginal end of said rod, and with said rod seal tube having means forming an outlet connected to said produced fluid outlet.

14. The downhole pump of claim 10 wherein said upper and lower pistons are each formed with a large diameter and a small diameter portion;

said upper and lower cylinders are each formed with a large diameter and a small diameter portion;

said large and small diameter portion, respectively, of

said cylinders receiving said large and small diameter portion, respectively, of said pistons.

15. The downhole pump of claim 14 wherein said small diameter portion of said upper cylinder is separated from the pump body by an annulus, means by which said annulus is flow connected to the production exhaust so that fluid can flow into and out of said annulus.

16. The downhole pump of claim 10, wherein said valve assembly includes a valve body and said means responsive to movement of said rod includes a traveling 14 passageways are alternately connected together by the action of said traveling valve element as it reciprocates within said valve body.

UNITED STATES PATENT'VOFFICE QETIFICATE 0F CORRECTION Patent No. 3 915, 595 Dated October 2 2 1975 InventorQ) George Roeder It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[34 7 on Cover Sheet should read "Double-Ended Hydraulically Actuated Downhole Pump".

Column 1, the title should read "Double-Ended Hydraulically Actuated Downhole Pump".

Column 9, claim 2, line 39, substitute --pistonfor "portion".\

Column 12, claim 12, line 30, correct the spelling of "lengths".

Signed and Sealed this twenty-third 0f March 1976 [SEAL] A ttes t:

RUTH C. MASON C. MARSHALL DANN Arresting ()jfz'cer Commissioner oflarents and Trademarks 

1. In a downhole hydraulically actuated pump assembly having a piston driven engine, a connecting rod attached to the piston, a pump connected to be driven by the connecting rod, and a control valve arranged to control power fluid flowing to and from the engine so that reciprocation of the engine piston causes the pump to lift fluid, the improvement comprising: said control valve includes a valve body (65), a fixed sleeve 81, and a valve element (67) slidably received about said fixed sleeve and within said valve body; said valve body, valve element, and fixed sleeve being concentrically arranged about said connecting rod; spaced upper and lower flats (76, 77, 78) on said connecting rod, means forming a power fluid annulus (75) between said connecting rod and valve element, means forming a spent power fluid annulus (98) between said connecting rod and pump body, said power fluid annulus being spaced from said spent power fluid annulus by at least part of said fixed sleeve; means forming a chamber (82) between said valve body, fixed sleeve, and valve element for causing said valve element to reciprocate when power fluid is flow connected thereto; an annular chamber (80) formed between said connecting rod and the interior of said fixed sleeve, flow passageway means (92 and 88) formed in said valve body and connected to said engine; said lower flat being comprised of two spaced undercut areas of a length to conNect together said power fluid annulus (75), annular chamber (80), and chamber (82) when said connecting rod is in an upper position, to cause the valve element to shift upward, thereby connecting together said power fluid and said spent power fluid flow passageways of the engine in a manner to cause a piston of the engine to stroke downwards; means by which said upper flat connects together said chamber (82) and said spent power fluid annulus (98) when the rod downstrokes to thereby cause the valve element to shift downward whereupon said power fluid and said spent power fluid flow passageways of the engine are connected together in a manner to cause a piston of the engine to stroke upwards.
 2. A hydraulically actuated downhole pump assembly comprising a main body having upper and lower cylindrical chambers spaced from one another by a control valve assembly; said upper and lower cylindrical chambers, respectively, having upper and lower pistons, respectively, reciprocatingly received therein; a connecting rod connected to said upper and lower pistons and adapted to stroke the pistons in either of two directions, a marginal intermediate portion of said connecting rod being received through said control valve assembly; means by which reciprocal action of said rod controls the action of said control valve assembly; said upper piston dividing said upper cylinder chamber into an upper production chamber and a lower engine chamber; said lower piston dividing said lower cylinder chamber into an upper engine chamber and a lower production chamber; means including a flow conduit forming a production fluid inlet through part of said main body and into said upper and lower production chambers so that production fluid from a production formation can flow thereinto; means including a flow conduit forming a produced fluid outlet through part of said main body and from said upper and lower production chambers so that produced fluid can flow from said downhole pump; means forming a power fluid flow path which extends into said main body, through said upper piston, through at least a marginal length of said connecting rod, and to said control valve assembly; means forming a first transfer fluid flow path connected from said control valve assembly to said lower engine chamber; means forming a second transfer fluid flow path connected from said control valve assembly to said upper engine chamber; means forming a spent power fluid flow path connected to flow from said control valve assembly, through a marginal length of said connecting rod, through said upper engine cylinder, through said lower piston, through said lower production chamber, and into flow communication with said produced fluid outlet; and means responsive to reciprocal movement of said connecting rod for causing said control valve assembly to connect said first transfer fluid flow path to said power fluid flow path, and said spent power fluid flow path to said second transfer fluid flow path when said rod strokes in one of two directions; and, to connect together said second transfer fluid flow path to said power fluid flow path, and said spent power fluid flow path to said first transfer fluid flow path when said rod strokes in the other of two directions; so that fluid pressure effected in said lower and upper engine chambers causes produced fluid to flow from said upper and lower production chambers.
 3. The downhole pump of claim 2 wherein said control valve assembly includes diametrically opposed spaced upwardly extending and downwardly extending rod seal assemblies, spaced marginal lengths of said connecting rod being axially positioned within said seal assemblies; the outer surface of said marginal length of said rod being spaced from the inner surface of said seal assembly to form an annulus therebetween; a port in said marginal length of said rod communicating said annulus with the interior of said rod; said annulus of said upwardly extending seal assembly forming part of said power fluid flow path; said annulus of said downwardly extending seal assembly forming part of said spent power fluid flow path.
 4. The pump of claim 3 wherein part of said spent power fluid outlet includes a lower marginal end portion of said connecting rod downwardly extending from said lower piston and through said lower production chamber; a lower rod seal tube having means for sealingly receiving a lower marginal end of said rod, and with said rod seal tube having means forming an outlet connected to said produced fluid outlet.
 5. The downhole pump of claim 4 wherein said control valve assembly includes a traveling element slidably received therein and slidable from a first to a second position for properly aligning the recited passageways together so that fluid flow can occur therethrough.
 6. The pump of claim 2 wherein said means responsive to reciprocal movement of said connecting rod includes a traveling element slidably received therein and slidable from a first to a second position for aligning the various flow passageways together.
 7. The pump of claim 2 wherein said power fluid flow path includes an upper seal means located above said upper production cylinder and sealingly receiving an upper marginal length of said connecting rod; said control valve assembly includes diametrically opposed spaced upwardly extending and downwardly extending rod seal assemblies, spaced marginal lengths of said connecting rod being axially positioned within said seal assemblies; the outer surface of said marginal length of said connecting rod being spaced from the inner surface of said seal assembly to form an annulus therebetween; a port in said marginal length of said rod communicating said annulus with the interior of said connecting rod; said annulus of said upwardly extending seal assembly forming part of said power fluid flow path; said annulus of said downwardly extending seal assembly forming part of said spent power fluid flow path; said power fluid flow path formed through the upper marginal end of said connecting rod being connected to said annulus of said upwardly extending seal assembly.
 8. The downhole pump assembly of claim 2 wherein said upper and lower pistons are each formed with a large diameter and a small diameter portion; said upper and lower cylinders are each formed with a large diameter and a small diameter portion; said large and small diameter portion, respectively, of said cylinders receiving said large and small diameter portion, respectively, of said pistons.
 9. The downhole pump assembly of claim 8 wherein said small diameter portion of said upper cylinder is separated from the pump body by an annulus, means by which said annulus is flow connected to the production exhaust so that fluid can flow into and out of said annulus.
 10. In a downhole hydraulically actuated pump assembly having a fluid powered engine connected to drive a production pump, a source of power fluid connected to the engine, with the production pump being connected to a source of production fluid and to a produced fluid outlet, and with the pump assembly being connected so that spent power fluid and produced fluid flows from the pump assembly uphole to the surface of the ground, the improvement comprising: said pump assembly comprising a main body having means forming an upper cylinder chamber, a lower cylinder chamber, a control valve, with said upper and said lower chambers being spaced from one another by said control valve; a connecting rod, an upper and lower production seal means, an upper piston, a lower piston, said upper piston dividing said upper chamber into an upper production chamber and a lower engine chamber; said lower piston dividing said lower chamber into an upper engine chamber and a lower production chamber; said connecting rod being connected to said pistons and extending through said upper production seal means, said upper production chamber, said upper piston, said loWer engine chamber, said control valve means, said upper engine cylinder, said lower piston, said lower production chamber, and through said lower seal means; an upper rod seal tube, said upper rod seal tube being flow connected to said control valve and extending into said lower engine chamber; a lower rod seal tube, said lower rod seal tube being flow connected to said control valve and extending into said upper engine chamber; said lower production seal means being separated from said lower piston by said lower production chamber; said upper production seal means being separated from said upper piston by said upper production chamber; means forming a first transfer flow passageway from said control valve into said lower engine chamber, means forming a second transfer flow passageway from said control valve into said upper engine cylinder; means forming a power fluid flow passageway extending from the interior of an upper end of said pump, into the upper end of said connecting rod, through a marginal length of said connecting rod, into said upper rod seal tube and to said control valve; means forming a spent power fluid flow passageway from said control valve, into said lower rod seal tube, into said connecting rod, through a marginal length of said connecting rod, into said lower production seal means, and to the produced fluid outlet; said control valve including means responsive to movement of said connecting rod in one direction for causing said first transfer flow passageway to be connected to said power fluid flow passageway while said second transfer flow passageway is connected to said spent power fluid flow passageway; and, means responsive to movement of said rod in another direction for causing said first transfer flow passageway to be connected to said spent power fluid flow passageway while said second transfer flow passageway is connected to said power fluid flow passageway.
 11. The downhole pump of claim 10 wherein said control valve includes a traveling element slidably received therein and slidable from a first to a second position for properly aligning the recited passageways together so that fluid flow can occur therethrough.
 12. The downhole pump of claim 10 wherein said control valve includes diametrically opposed spaced upwardly extending and downwardly extending rod seal assemblies, spaced marginal lengths of said connecting rod being axially positioned within said seal assemblies; the outer surface of said marginal length of said rod being spaced from the inner surface of said seal assembly to form an annulus therebetween; a port in said marginal length of said rod communicating said annulus with the interior of said rod; said annulus of said upwardly extending seal assembly forming part of said power fluid flow path; said annulus of said downwardly extending seal assembly forming part of said spent power fluid flow path.
 13. The downhole pump of claim 10 wherein said spent power fluid outlet includes a lower marginal end portion of said connecting rod downwardly extending from said lower piston and through said lower production chamber; a lower rod seal tube having means for sealingly receiving a lower marginal end of said rod, and with said rod seal tube having means forming an outlet connected to said produced fluid outlet.
 14. The downhole pump of claim 10 wherein said upper and lower pistons are each formed with a large diameter and a small diameter portion; said upper and lower cylinders are each formed with a large diameter and a small diameter portion; said large and small diameter portion, respectively, of said cylinders receiving said large and small diameter portion, respectively, of said pistons.
 15. The downhole pump of claim 14 wherein said small diameter portion of said upper cylinder is separated from the pump body by an annulus, means by which said annulus is flow connected to the production exhaust so that fluid can flow into and out of said annulus.
 16. The downhole pump of claim 10, wherein said valve assembly includes a valve body and said means responsive to movement of said rod includes a traveling valve element concentrically arranged and slidably received respective to said valve body and said connecting rod; means by which said first and second transfer flow passageways, and said power and spent fluid flow passageways are alternately connected together by the action of said traveling valve element as it reciprocates within said valve body. 